HABUR, Turkey (Reuters) - Turkish President Tayyip Erdogan said Iraqi Kurds would go hungry if his country halts the flow of trucks and oil across the border with northern Iraq and warned that all military and economic measures were on the table against its neighbour.

The comments, some of the harshest yet from Erdogan about Monday’s referendum in Iraq’s semi-autonomous Kurdish region, came as Iraqi troops joined the Turkish army for military exercises near Turkey’s border with northern Iraq.

While initial results indicated overwhelming support for independence, Turkey - long northern Iraq’s main link to the outside world - sees the referendum as a threat to its own security, fearing it will inflame separatism among its Kurdish population.

“(They) will be left in the lurch when we start imposing our sanctions,” Erdogan said in a speech broadcast live on television. “It will be over when we close the oil taps, all (their) revenues will vanish, and they will not be able to find food when our trucks stop going to northern Iraq.”

Turkey, which is home to the region’s largest Kurdish population, is battling a three-decade Kurdish insurgency in its southeast, which borders northern Iraq. Erdogan said on Monday that traffic was only being allowed to cross from the Turkish side of the border into Iraq.

Erdogan has repeatedly threatened economic sanctions, but has given few details. Hundreds of thousands of barrels of oil a day flow through a pipeline in Turkey from northern Iraq, connecting the region to global oil markets.

Iraq, including the Kurdish region, was Turkey’s third-largest export market in 2016, according to IMF data. Turkish exports to the country totalled $8.6 billion (6.41 billion pounds), behind Germany and the United Kingdom.

MILITARY MEASURES

Erdogan said all potential measures - including economic and military initiatives that involved land and air space - were on the table, adding that Iraqi Kurds would be incapable of forming a state.

“They don’t have an idea on how to be a state. They think that they are a state just by saying it. This can’t and won’t happen,” he said.

Iraqi soldiers joined Turkish troops for military exercises in southeast Turkey near the border with Iraq on Tuesday, a Reuters witness near the border said, as the two countries coordinate steps in response to the referendum.

A small group of soldiers holding an Iraqi and a Turkish flag walked across the dusty plain where the exercises, launched last week, were being held 4 km (2.5 miles) from the Habur border gate.

The flags were then held aloft from the top of an armoured personnel carrier. National and international media observed the exercises from the main highway leading to the border gate.

The Turkish president also accused Masoud Barzani, the president of the Kurdistan Regional Government, of “treachery” over the vote.

“Until the very last moment, we weren’t expecting Barzani to make such a mistake as holding the referendum. Apparently we were wrong,” Erdogan said.

“This referendum decision, which has been taken without any consultation, is treachery.”

Additional reporting by Ece Toksabay and Dirimcan Barut in Ankara and Ezgi Erkoyun in Istanbul; Writing by David Dolan; Editing by Daren Butler and Giles Elgood